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History of USGS Astrogeology image processing software

Integrated System for Imagers and Spectrometers (ISIS) has been a staple
for the cartographic and scientific analysis of planetary image data
since 1992 with a heritage reaching back to 1971. The key strength of
ISIS is its ability to rigorously "control" planetary image data,
calculating the proper location and orientation of the observer and the
target. It is developed and maintained by the U.S. Geological Survey
using funds from the NASA Planetary Geology and Geophysics Cartography
Program and various U.S. and international missions. ISIS forms the
backbone for some ground data systems that process raw spacecraft data
into products suitable for archiving in the NASA Planetary Data System
(PDS). For example, processing the Lunar Reconnaissance Orbiter Camera
(LROC) and Mars Reconnaissance Orbiter (MRO) HiRISE images rely on
ISIS.

The software has evolved numerous times to keep up with advances in
computing technology. The following outlines the progression of the
software since its inception:

In 1971, Astrogeology's involvement in the Apollo program ended, and
many personnel in computer/cartographic related positions
transferred to Earth Resources Observation and
Science (EROS) Center, to other federal agencies, or took jobs in the
private sector. James Crawforth (also known as Jim) and Alex Acosta
remained and established
a computer division to serve the Flagstaff Field Center. Development
of the unnamed image processing software package began on a Digital
Equipment Corporation (DEC) PDP-11/20 minicomputer with 8 K bytes of
memory, two 2.5 megabyte removable disks, an 800 bpi tape drive, a card
reader, and a teletype terminal. The PDP-11/20 ran a single user DOS/Batch
operating system that executed programs which were read from keypunch
cards. The images were printed on film transparencies with an
$80,000 Optronics International Inc. filmwriter, and then viewed by
the analyst.

In the late 1970s, the unnamed USGS image processing software was
migrated to a DEC PDP-11/45 minicomputer with 256 KB of memory and
larger 40 MB disks the size of washing machines, and ran the RSX-11M
operating system. This migration allowed a host of advances such as
(a) multiple users having access to the computer through VT52 black
and white video terminals, (b) programmers could develop applications
using as much as 32 KB of memory, and (c) a new method to view
images: on a screen using a DeAnza 512x512 Frame Buffer display
system! This configuration became known as the Flagstaff Image
Processing System (FIPS).

In the early 1980s, DEC introduced their new VAX/VMS computers which
allowed for virtual addressing. Developers no longer had restrictions
on the size of the programs they developed. This major change in the
computing environment allowed the Astrogeology programming team, led
by Eric Eliason, to convert the software from FIPS to the Planetary
Image Cartography System (PICS). The Transportable Application Executive
(TAE) was chosen as the user interface, and the programs migrated to run
on the VAX/VMS computers. The PICS software package was a popular tool
in the planetary science community because of its ability to process
Viking Orbiter, Voyager, Magellan, Landsat, and various other spacecraft
imagery.

In the late 1980s, the requirement to handle large volumes of complex
data acquired by new instruments significantly changed the requirements
on Astrogeology's imaging processing software. PICS could only handle
images with 7 or fewer bands, and left the user to manage each band as
a separate file. The Galileo mission's Near-Infrared Mapping Spectrometer
(NIMS) instrument, a hyperspectral imager capable of collecting images
with up to 408 bands, was the first to show the limitation of the PICS
software. To efficiently handle many bands for
a single image, the PICS software package had to be fundamentally
redesigned. The new package, the Integrated System for Imaging
Spectrometers (ISIS) came into existence under the guidance of the
designer Jim Torson and developer Kris Becker. After passing through
an internal version 1.0 prototype, this software was released as
ISIS 2.0.

In the early 1990s, the Clementine mission collected hundreds of
thousands of images with the Ultraviolet/Visible (UVVIS) and Near-Infrared
(NIR) cameras. The hardware and software requirement to process the
large volume of data led to a transition to new hardware and the use of
the Oracle data base system to streamline the processing methods. Perl
scripts were used to run repetitive tasks and also introduced at this
time. These innovations were largely incompatible with PICS.

Janet Richie uses TAE for her processing work

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Cost also drove the change from PICS to ISIS. PICS operated on the aging
and expensive VAX/VMS computer system. The planetary community often
lamented the $50,000 price tag for a single machine with a display
device. At this time, UNIX began to make a push in the computing
world. Astrogeology's computer group decided to merge the PICS and
ISIS software and move to the SunOS and DEC OSF1 platforms under
the UNIX operating system. The integration of PICS and ISIS was led
by Kay Edwards, leading to the creation of ISIS 2.1.

During the late 1990s, ISIS continued to grow in both number of
applications and the supported operating systems. Software to process
data from Galileo Solid State Imager, Imager for Mars Pathfinder, Mars
Global Surveyor Mars Orbiter Camera, Mars Odyssey THEMIS, and other
instruments were added. The software was ported to the Linux operating
system as the demand for cheaper computers with "Open-source software"
increased. The ISIS 2.1 display software allowed for visual image
analysis directly on the user's desktop instead of requiring
specialized monitors. ISIS made huge gains in usage by non-USGS
customers, especially with the increased focus on cartographic
processing. With the popularity of the ISIS software package, the
meaning of the acronym "ISIS" was changed to Integrated System for
Imagers and Spectrometers.

By 2001, Astrogeology recognized that the cost and time to maintain
the ISIS software package was becoming more difficult as different
components of the software system became obsolete or became harder
to manage. Users constantly asked for TAE to be replaced by a
standard Graphical User Interface (GUI). The ISIS development staff
could not use some of the powerful debugging tools that were
available, because they did not function well on computer code
written in Fortran or C. Many of the Open-source Application
Program Interfaces (APIs) were only
available in C++ or Java, and thus not available for usage in ISIS.
The cube file formats did not efficiently support missions that
acquired data with line scan cameras. In order to take advantage
of new capabilities in the computer technology, the decision was
made to modernize ISIS. Jeff Anderson led the effort to convert
the ISIS programs written in Fortran/C to C++, creating ISIS 3.

Screenshots of ISIS Application GUIs:

The GUIs replaced the outdated TAE interface in ISIS. Programs
now have meaningful names and are task-specific so that ISIS
is easier and faster to use.

Crop

All programs have dialog boxes for selecting files to process,
as shown in this screenshot. Crop was called dsk2dsk
in earlier versions of ISIS, one of many programs renamed to
more meaningful names in ISIS 3.0.

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Lowpass

Lowpass is one of several task-specific programs that was
once part of the boxfilter program.

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Sharpen

Sharpen is another task-specific program that was once
part of the boxfilter program. With the original boxfilter
program broken into several smaller programs, fewer
parameters are required. The program names are more meaningful
making ISIS easier to learn and use.

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A second driver for the creation of ISIS 3 was a new wave of
instruments that produced gargantuan images. For example, the
Mars Reconnaissance Orbiter HiRISE camera routinely acquires 1000
Megapixel images. Even more challenging was the need to produce
controlled mosaics consisting of thousands of large images from the Lunar
Reconnaissance Orbiter Camera Narrow Angle Camera (NAC). Solving
for the position and orientation of the spacecraft required handling
complex manipulations of extremely large matrices. Even the
efficient access of ancillary data, historically stored as text in
file headers, became an issue. ISIS 3 underwent a series of major
updates to improve the efficiency and accuracy of the map projected
output from the software.

Today, ISIS 3 continues to evolve to meet the needs of users within and
outside the Astrogeology Science Center. It remains the premier software
package for putting pixels in the correct location in digital space. Releases
of new versions occur about 4 times a year, with major releases every year
or two. Experience suggests that this pace strikes the right balance
between stability and timely improvements to ISIS 3. It should be noted
that the data ISIS uses (e.g., SPICE) are frequently updated and small
patches are sometimes put out in between the scheduled releases. The
latest version of ISIS 3 can be found here
ISIS 3.